The effect of suspended solids on disinfecting process for drinking water in Peshawar valley

Drinking water samples were collected from consumer tap at 12 different locations in Peshawar valley during the month of August and September 2003. In Peshawar, the subsoil water is used for drinking and other purposes and supplied to the consumers through underground distribution lines. Chlorination is the disinfecting practice carried out by water management authorities in,the area. These samples were examined for the presence of residual chlorine, microorganisms and related parameters. On the basis of this study, it was evaluated that a lot of suspended matter is present in most of the samples, which may be due to geographic nature of the area where heavy rain is common during the monsoon that alters the suspended matter composition of water or may be due to leakage in the old corroded distribution lines, providing an opportunity to both microorganisms and suspended matter to penetrate in the distribution circuit. The suspended matter imparts turbidity, which shields microorganisms against disinfection by adsorbing chlorine at their surface and unavailable for the purpose. Statistical findings show that increase of one unit in the suspended matter causes an increase of 3.74 units in coliform bacteria.